Copepod Crustacean: average sizes mm. Copepod. Copepod motion. Reconstructed feeding currents

Transcription

1 Introduction to Oceanography Lecture 24: Nekton Announcements: Review Session: Thursday, Dec. 7, 3:00-3:50pm, Young CS24 Video Screening: Wednesday, Dec. 6, 3:00-3:50pm, Young CS76 True s Beaked Whale Mesoplodon mirus Video by R. Edler, from de Soto et al., 2017, Creative Commons License Mako Shark, Isurus oxyrinchus, photo by Mark Conlin, SWFSC Large Pelagics Program, Public Domain, Copepod Crustacean: average sizes mm Max size ~ 25 mm ~ 9000 known species Voracious feeder/filterer Forms key food for many other larger plankton and nekton Photo Alfred Wegener Institute, er_upload/news/press_relea ses/2006/3._quarter/plankton 3_p.jpg Copepod Image from Museum Victoria, Australia, biol.html Copepod motion Reconstructed feeding currents 1

2 Copepod motion Video by Murphy et al., Georgia Tech (2011) Breaching Mobula ray, photo by Nick Bonzey, Flickr, Creative Commons A S-A 2.0, Diurnal Migrating Plankton Upwards vertical migration by night Downward vertical migration by day Occurs in some species of every major group of zooplankton Some nekton & possibly phytoplankton as well Polar Seasonal Vertical Migration North Atlantic copepods & Antarctic krill undergo seasonal vertical migrations Feed during spring/summer Dive to ~ m during winter Diapause: slow metabolism, no feeding Lay eggs at depth that slowly float upwards Return to surface in spring Planktonic Patchiness Plankton are often found in patches Physically due to: Gyre circulations, water mass boundaries, turbulence & mixing, wind-induced mixing, wave action Biologically due to: Ecosystem scale (water masses), spring blooms, different growth rates of different species, reproductive cycles, grazing/predation, diurnal migration Anchovies, NOAA image, Public Domain, htm NASA/MODIS, Public Domain, m.jpg 2

3 Multicellular life Origin of Animals Rise of oxygen: ~2,500 million million years ago Photosynthetic autotrophs pump out O 2 Atmosphere goes from <<1% to 20% O 2 Allows respiration to occur Evolution of multicellular heterotrophic animals. Dickinsonia, Verisimilus, Creative Commons A S-A 2.5, Cyclomedusa, Verisimilus, Creative Commons A S-A 2.5, Anomalocaris, Photnart, Public Domain, Mahttp://commons.wikimedia.org/wiki/File:Ano malocarisdinomcanb.jpg ~510 Ma 505 Ma Sardines, by James Kilfiger, Creative Commons A S-A 3.0, Ma What kinds of Animals exist? Invertebrates No internal skeletons Includes simplest animals, evolved first Vertebrates Internal backbone Evolved from invertebrates Plankton NEKTON Lifestyle classification: organisms that swim strongly in the water column (able to overcome currents). Must be big enough to swim fast & far. Food web of Charleston Bump, NOAA/Weaver and Sedberry, 2001, Public Domain, a/foodweb.html Invertebrates - no internal skeleton -- some species have firm cuttlebone support structures Subdivision of Molluscs ( head-foot ) Most complex and intelligent molluscs Mostly nektonic or nektobenthic lifestyle Swim along the bottom Nautilus, video by Shizhao, Creative commonsc A S-A 3.0, autilus.ogg Nautilus Caribbean Reef Squid, Jan Derk, Public Domain, Mastigoteuthis_flammea, Carl Chun, Public Domain, lammea.jpg 3

4 Include squid, octopus, cuttlefish, nautilus Have three hearts, blue blood copper based; blue when its oxygenated ours is iron based; red when oxygenated 650 living species, around at least ~ 500 Mya Many change color rapidly Reef octopus, Okinawa, video by goebelte,, Ordovician nautiloid ( Ma), China Photo Dloyd,, Creative Commons A S-A 3.0, Video by Joel Ang, as.jpg Motion Some swim by moving tentacles/fins Video by Vecchione and Young, Smithsonian Museum of Natural History (1997) Vie et Milieu, 47: Jet propulsion by forcing water through siphon ages/vids/cfvsfish.mpg Video by Vecchione and Roper, Smithsonian Museum of Natural History (1991) Bulletin of Marine Science, 49(1-2): Giant squid up to 18 m long Deep Water ~ 2000 m Feed on what? Hunted by sperm whales Cuttlefish, squid, & octopi: Color change ability Intelligence Short-range jet propulsion Advanced nervous systems Acute eyesight Other special adaptations? Why such unique adaptations? National Institute of Water and Atmospheric Research - NIWA Greta Point, Wellington, New Zealand, Public Domain(?), SQUID/clyde_squid_table.jpg Caribbean Reef Squid, Jan Derk, Public Domain, Fish Octopus vulgaris, photo by Gronk, Wikimedia Commons, Creative Commons A S-A 3.0, v.jpg Amberjack, Public Domain, 4

5 Fish Jawless Fish (Class Agnatha) Jawless fish, flexible snake-like bodies, no paired appendages for movement Earliest related fossils ~ 500 Mya Survive by sucking on wounds of other fish, eating out interiors Include hagfish (right) and lampreys (below) Self-camming flesh pullers Image Patricia J. Wynne, 2004, Natural History Magazine/American Museum of Natural History, me/slime.htm Becomes slimy when provoked! Pieni Tietosanakirja (Finnish Encyclopedia), , Public Domain, Photo by Drow male, Wikimedia Commons, Creative Commons A S-A 3.0, ons/6/6f/diversas_lampreas.1_- _Aquarium_Finisterrae.JPG Hagfish face a similar problem to cephalopods they re soft! Their defense? Slime predators when provoked! July 13, 2017 Video by Nimrod Levy (U. British Columbia), YouTube, Photo by Oregon State Police Bony Fish 30,000 living species: Most diverse of all vertebrate groups 90 million tons removed by humans each year Equivalent to ~15 kg per person per year US residents ate about 7 kg/person per year in 2003, more goes to fertilizer and animal feed products. Buoyancy Many have swim bladders (gas filled sac) Allows fish to maintain position in water column Some swallow air at surface, release at depth Some have gas gland that transfers gas from blood Swim bladders are a hindrance to bottom dwellers and fast swimmers (tuna) shark, CA, photo by Ed Bierman, Creative Commons A 2.0, 5

6 Shape of Fast-swimming Fish Fineness = diameter/length 0.25 in tuna Minimal drag at high speed (large Reynolds number) Aspect ratio of tail = span/chord most efficient for generating lift Figure John Merck, U. Maryland, ss.gif Teardrop shape minimizes frictional drag Thrust by waves of body motion and fins Fins Pelvic and pectoral: turning, braking, balance, little thrust Dorsal & anal: stability and steering Caudal (tail): Most thrust Video by onitube, YouTube, Bony Fish A fish s hinged tail generates efficient forward motion U. Minnesota Computational hydrodynamics and biofluids laboratory, U. Michigan Museum of Zoology, _fish/structure_function/v04_id131_con_gillfun.jpg GILLS: extract dissolved oxygen from sea water. Oxygen-rich sea water diffusively exchanges with oxygen-poor blood in gills Faster swimming fish have bigger gills (and higher body temperatures) Coloration Counter-Shading: a type of crypsis Dark above -- blends with deep water Sargassum fish, photo by Art Howard/Ross et al, NOAA-OE, HBOI, Public Domain, s/logs/oct31/media/fig1.html Stone flounders, photo by Takahashi, Wikimedia Commons, Public Domain, tus_camouflage.jpg White below -- blends with sky Great white shark, photo by Sharkdiver68, Wikimedia Commons, Public Domain, Plankton? Nekton Garibaldis, NOAA image, Public Domain, Benthos Food web of Charleston Bump, NOAA/Weaver and Sedberry, 2001, Public Domain(?), a/foodweb.html 6

7 Habitats Infauna: Live in sediment and rocks Razor clams burrow into the sand or mud Habitats Epifauna: Live on the surface Sea anemone Purple Sea Urchin Drawing from City of Barnstable, Mass. /ShellfishPics/razrclam.gif Photo by David Ansley, Wikimedia Commons, Creative Commons A 2.5, Photo by Esculapio, Wikimedia Commons, Creative Commons A S-A 3.0, PG Photo by Tomasz Sienicki, Wikimedia Commons, Creative Commons A S-A 3.0, 5_ubt.jpeg Habitats Nektobenthos: Swimmers living on the bottom Examples: Octopus, shrimp, halibut Horn shark, La Jolla, CA, photo by Magnus Kjaergaard, Wikimedia Commons, Creative Commons A S-A 3.0, Nutrition Autotrophs are the base of the food web: Photosynthesizers (usually) Algae live in the photic zone (not found below the photic zone) Kelp beds: autotrophic benthic algae High productivity or low productivity? Neritic or Oceanic? Photo by Stef Maruch, Flickr, Creative Commons A S-A 2.0, Nutrition Heterotrophs: Eat others to live Eating Styles of Benthic Heterotrophs Suspension Feeders Filter Feeders Deposit Feeders Active Herbivores Active Carnivores Crinoid, a suspension feeder, photo by Richard Ling, Wikimedia Commons, Creative Commons A S-A 3.0, a_australis_passion_flower_feather_star.jpg 7